6 March 2010 - Size of bowl and amount of water

Location:Beltsville Agriculture Research Center , MD
Conditions:  Sunny, upper 80's
Start: 7:15 a.m. April 6
End: 5:00 p.m. April6
Habitat:Mature deciduous woodland with Spring Beauty understory
Bees: Andrena, Osmia, Lasioglossum, Ceratina, Nomada
Experiment: 3.25 ounce white solo cups  were alternated with a completely filled 12 ounce Party store white (on outside and inside) plastic drink cup and the same drinking cup filled half full.  Bowls were spaced 5 m apart and filled with soapy water (unscented laundry detergent and tap water). 

Results:

Site Number 1

	1	2	3	4	5	6	7	8	9	10	Mean
3.25	2	4	2	3	2	20	6	2	0	3	4.40
12 Full	0		3	3	4	9	9	3	1	5	4.11
12 Half	0	1	3	1	2	10	2	1	1	2	2.30

Pretending the data were normally distributed resulted in an F=0.719, P=.4814.  A Kruskal-Wallace test yielded a P=0.14.

Site Number 2

	1	2	3	4	5	6	7	8	9	10	Mean
12 Full	4	1	5	2	3	5	6	2	5	15	4.80
12 Half	3	4	0	1	5	5	0	0	0		2.00
3.25	4	3		6	0	6	6	11	7	2	5.00

ANOVA: F=0.2454, P=0.1064.   KRUSKAL-WALLACE: P=0.06

Combining both datasets (without getting fancy and adding a factor for site)

ANOVA: F=2.842, P=0.06706.  KRUSKAL-WALLACE: P=0.02

Note that Site Number 2 was the same site run the previous day under almost identical weather conditions, but now with many more captures...almost surely due to putting in sufficient laundry detergent this time....

Note also that when we indicate that a bowl or cup is full that it is actually a few mm shy of the rim...it just is not practical to fill them to the rim given the unevenness of the ground.

Results indicate that there is no statistical difference between the white 3.25 ounce bowls and the 12 ounce cups when both are full, but that catch is decreased by half when the cup is half full and that is statistically different from the two full bowls (paired tests not presented here). 

The practical ramifications here is that when running traps that use deep cups it is best to fill them to the top even if rain dilutes the mix.

4 April 2010 - Bowl Size and Position

Location: Hardesty, MD
Conditions:  Sunny, 70's
Start: 9:00 a.m. April 4
End: 6:00 p.m. April 4
Habitat:Mature mixed woodlands with Spring Beauty understory
Bees: Andrena, Osmia, Lasioglossum, Ceratina, Nomada
Experiment: 3.25 ounce white solo cups  were alternated with a completely filled 16 ounce Walmart store plastic drink cup that was red on the outside and white on the inside and the same Walmart Drinking cup buried so that it stood up about the same distance as the 3.25 ounce solo cup, and then another Walmart drinking cup that was cut down to the same height (it was about the same diameter) as the 3.25 ounce solor.  Bowls were spaced 5 m apart and filled with soapy water (dawn dishwashing detergent and tap water). 

Results:

	1	2	3	4	5	6	7	8	9	10	Mean
16 oz. Buried	0	1	0	1	5	2	9	2	0	4	2.40
3.25 Oz.	7	0	1	2	2	5	n	7	6	4	3.78
Cut 16 oz.	1	1	2	0	0	8	6	5	2	0	2.50
16 oz.	1	1	1	3	2	2	10	0	4	1	2.50

Note that all the Walmart bowls had essentially the same average catch, but the solo bowl bowls was higher by a bit over a bee per bowl....

That said, a one-way ANOVA indicated that such a difference wasn't significantly different from the other means (f=0.5401, P=0.6819), a square root transformation for count data didn't improve anything.

Its possible that the red on the outside had a slight impact, but then again, most bees cannot see red and this was a bright red.

So, not a lot of evidence for an effect of cup size or height above the ground, but perhaps a difference between bowls types...though the evidence is weak.

5 April 2010 - 5 March 2010 - 3.25 oz. vs 12 oz. full vs 12 oz. half

Location: Beltsville Agriculture Research Center, MD
Conditions:  Sunny, 80's
Start: 10:30 a.m. April 5
End: 5:00 p.m. April5
Habitat:Mature deciduous woodlands with Spring Beauty understory
Bees: Andrena, Osmia, Lasioglossum, Ceratina, Nomada - Many bees flying around

Experiment: 3.25 ounce white solo cups  were alternated with a completely filled 12 ounce white party store cup and a half-filled white 12 ounce party store cup.  Bowls were spaced 5 m apart and filled with soapy water (unscented laundry detergent and tap water). 
Problem:  I only sprinkled a little laundry detergent into the several gallons of water for the experiment...apparently this was not sufficient, as I saw bees land on the surface tension and fly or crawl out.   I will go back to a more concentrated solution.

Despite low catch there was an indication of a bowl effect with the 3.25 ounce bowls.  However, this needs to be repeated as the 3.25 ounce bowls had been used many times before and may have a lot of residual soap on them.  The 12 oz. bowls had never been used before.

	1	2	3	4	5	6	7	8	9	10	Average
12 Oz. Full	0	0	5	0	0	2	0	1	1	0	0.90
12 Oz. Half	0	0	1	0	2	0	2	0	0	0	0.50
3.25 Oz. Full	2	0	0	0	5	6	4	1	4	0	2.20

5 March 2010 - 3.25 oz. vs 12 oz. full vs 12 oz. half

Location: Beltsville Agriculture Research Center, MD
Conditions:  Sunny, 80's
Start: 10:00 a.m. April 5
End: 4:30 p.m. April5
Habitat: Field with scattered trees, no apparent flowers.
Bees: Andrena, Osmia, Lasioglossum, Ceratina
Experiment: 3.25 ounce white solo cups  were alternated with a completely filled 12 ounce white party store cup and a half-filled white 12 ounce party store cup.  Bowls were spaced 5 m apart and filled with soapy water (unscented laundry detergent and tap water). 
Problem:  I only sprinkled a little laundry detergent into the several gallons of water for the experiment...apparently this was not sufficient, as I saw bees land on the surface tension and fly or crawl out.   I will go back to a more concentrated solution.

Despite low catch there was no strong indication of a bowl effect.

	1	2	3	4	5	6	7	8	9	10	Average
3.24 Oz. Full	0	0	0	0	0	0	0	0	0	1	0.10
12 Oz. Full	0	0	0	0	0	0	1	1	n	0	0.22
12 Oz. Half	1	0	0	0	0	0	1	1	0	0	0.30

31 March 2010 - Styrofoam cup vs plastic cup...soapy water vs glycol

Location: Hardesty, MD
Start: Morning, 27 March
End: 5:00 p.m.31 March
Habitat: Patuxent River, bottomland, young deciduous woods, many spring beauties in bloom
Bees: Andrena primarily
Experiment: 9 sets of 4 bowls.  At each set was 2 3.25 ounce white solo brand bowls and 2 Styrofoam 16 ounce cups laid in small square a bit more than one foot apart.  Each type of bowls was filled either with a detergent mix or a glycol mix (Walmart RV antifreezed, dyed red).  The capture was not removed the entire time.

Results 


Site Numbers are in the first row.  "n" refers to a bowl that was spilled or had no liquid.

	1	2	3	4	5	6	7	8	9	Average
Solo/Detergent	1	n	0	4	n	2	4	0	2	1.86
Solo/Glycol	3	0	n	n	2	4	4	0	1	2.00
Styrofoam/Detergent	0	1	0	0	0	1	0	0	0	0.22
Styrofoam/Glycol	0	0	0	n	0	0	0	0	0	0.00

Interpretation:  It is clear that there is a strong difference between the Plastic cups and the Styrofoam cups but not between glycol and soap.

 

3 April 2010 - Glycol vs Soapy Water

Location: Hardesty, MD
Start: 7:30 a.m. April 3
End: 6:00 p.m. April 3
Habitat: Patuxent River, bottomland, young deciduous woods, many spring beauties in bloom
Bees: Andrena, Osmia, Lasioglossum
Experiment: 24 bowls of 3.25 ounce white solo brand bowls laid in a transect through the woods and placed 5 m apart. Every other bowl was filled with a solution of soapy tap water (large squirt of blue dawn dishwashing liquid in a gallon of water). In the other bowls was placed a solution of soapy propylene glycol (large squirt of blue dawn dishwashing liquid in a gallon glycol). The glycol is RV glycol purchased from Walmart into which about 2 tablespoons of household bleach was added to remove the red dye, the concentration of the glycol was unknown but Walmart claims it will not freeze until you reach -51F (also untested).

Results below are detergent in the left column and glycol in the right column. They are presented as pairs, but in reality they are simply adjacent to one another in the transect. Numbers are total number of bees.

Detergent	Glycol
3	5
0	12
5	4
12	11
0	0
3	2
6	9
2	12
9	16
9	7
17	19
21	10
Totals
87	107

A straight t-test (numbers were normally distributed)

t: -0.6626 p(same): 0.51447

Did not indicate that the two treatments came from different sampling distributions and are thus not statistically different at the sample sizes presented.

95% conf. for difference between means: (-3.5499 6.8832)

So, the conclusion at least for this time, place, and community of bees is that soapy water and soapy glycol are equally effective.

2 April 2010 - Styrofoam / Solo Bowl Experiment

Location: Beltsville, MD
Start: Noon April 1
End: 9:30 a.m. April 2
Habitat: Bottomland Mixed forest with many spring beauties in bloom
Bees: Osmia, Andrena, Nomada
Experiment: 21 bowls each of 3.25 ounce white solo brand bowls and similar sized cut down styrofoam cups, the two types were alternated in a transect through the woods and placed 5 m apart.

Results below are styrofoam in the left column and solo in the right column. They are presented as pairs, but in reality they are simply adjacent to one another in the transect. Numbers are total number of bees.

Helping on the this experiment were Molly Passacantando and Lisa Guide (Many thanks).

Styro	Solo
9	18
2	3
1	8
1	7
0	4
0	5
1	6
0	8
3	2
5	12
3	8
0	5
2	15
1	11
0	17
n/a	15
1	3
0	10
3	19
5	21
7	18
	Totals
44	215

Results are extremely clear. Styrofoam captures are much less. Totals are much lower and in adjacent bowls capture in styrofoam is always lower.

Not sure why, both are bright white....possibly bees can climb out of Styrofoam more easily, but no sign of soggy bees on or near the cups.